Muffling device



July 18, 1939.

W. A. MORRISON MUFFLING DEVICE Filed April 6, 1937 HIS ATTORNEY.

Patented July 1s, 1939 2,166,218

UNITED STATES PATENT OFFICE MUFFLING DEVICE William A. Morrison, Easton, Pa., assigner to Ingersoll-Rand Company, Jersey City, N. J., a corporation of New Jersey Application April 6, 1937, Serial No. 135,221

4 Claims. (Cl. 121-35) This invention relates to muiing devices, and against a shoulder 33 of the back head 24 and more particularly to an exhaust muiing device is centralized with respect to the back head by for pneumatic tools of the percussive type. a projection 34 of the back head extending into One object of the invention is to effectively the sleeve- 5 suppress the sound waves induced by the emis- The sleeve 3| is of somewhat larger diameter '5 sion of the uid from the motor and to transform than the casing parts which it surrounds and the exhaust impulse into a substantially steady with which it cooperates to dene a space or stream. chamber 35 to r-eceive the exhaust uid issuing Another object is to equip the pneumatic tool from the exhaust port 28. The forward portion l0 with a simplified and effective muilling device 35 of the sleeve 3| is contracted to an approxi- 10` which will not add materially to the weight of mate conformation with the shape of the adjathe tool and which may be readily and cheaply Cent portion of the rock drill casing, and exreplaced. tending into the front end of the sleeve 3| is a Other objects will be in part obvious and in boss 3l carried by a ring 38 to which the front part pointed out hereinafter. end of the sleeve may be permanently secured, 15

In the drawing accompanying this speciicaas by welding. tion and in which similar reference numerals re- The ring 38 seats against the rear end of the fer to similar parts: front head 23, in the assembled positions of the Figure l is an elevation, in section, of a mufparts, and has a sliding t on the periphery of 2O ning device constructed in accordance with the the adjacent casing part. 20 practice of the invention and showing it applied Within the sleeve 3| are a series of partitions to a pneumatic tool of the percussive type, the 39, 40 and 4|, transversely arranged in the present latter being partly broken away, and instance, to divide the interior of the sleeve into a Figures 2 and 3 are transverse views taken plurality of expansion chambers 42, 43 and 44. through Figure 1 on the lines 2-2 and 3-3, The chamber 44 constitutes the nal expansion 25 respectively. chamber and in the portion of the sleeve 3| de- Referring more particularly to the drawing, hing it ale a plurality 0f DOI'DS 45 t0 afford 00mthe muiiiing device, designated in general by 20, munication between the chamber 44 and the is shown applied to a fluid actuated percussive atmosphere. tool 2| comprising a cylinder 22 and front and The chamber 43 is the intermediate expansion 30 back heads 23 and 24, respectively. chamber and that designated 35 constitutes the The interior of the cylinder constitutes a piston initial @XpaIlSOIl Chamber ntO WhCh the preschamber 25 containing a hammer piston 26 which sure uid is directly exhausted from the piston actuates a working implement 21 extending into chamber 25. As a preferred arrangement, the the front head and controls a free exhaust port partition 39 forming the upper bounding surface 35 28 for the piston chamber 25. The piston 26 is of the chamber 42 is disposed intermediate the of the differential type and has a stem 28 which exhaust port 28 and the valve mechanism 39 to extends slidably through a bushing 29 in the front prevent the exposure of the valve mechanism to end of the piston chamber to strike against the the direct chilling inuence of the expanded fluid Working implement 21. owing through the chamber 42. The partitions 40 'Ihe pressure fluid employed for actuating the 39, 49 and 4| are in the form of annular plates piston 26 may be distributed to the ends of the affixed to the sleeve and of which the inner and piston chamber 25 by suitable valve mechanism outer surfaces abut the cylinder 22 and the sleeve of which only the outer casing part 3D is shown. 3|, respectively. 'Ihe valve mechanism may, as illustrated, be ar- To the end that maximum suppression of the 45 ranged between the piston chamber and the back sound waves may be obtained in each chamber head 24 and be in communication with the ends the passages affording communication between of the piston chamber 25 through suitable ports the adjacent chambers are dened by conduits and passages (not shown). extending through the partitions and Secured to The muler 20 constructed in accordance with the inn-er surface of the sleeve 3|. A conduit 46 50 the practice of the invention is in the form of a is accordingly arranged in the partitions 40 to tubular member or sleeve 3| which surrounds the extend from a point near the partition 39 to a intermediate portion of the pneumatic tool compoint spaced from the partition 4| only a sumprising the cylinder 22 and the valve mechanism cient distance to permit the free egress of fluid 3U. The rearmost end 32 of the sleeve seats from the conduit 45 into the chamber 43. Simi- 55 larly, a conduit 41 is arranged in the partitions 4| and extends from the upper portion of the chamber 43 into the chamber 44.

Owing to the arrangement of the conduits with respect to the expansion chambers the exhaust fluid is required to travel a path of maximum length possible With the structure illustrated and a maximum dampening effect is, therefore, obtained in each chamber.

As is well known, under certain climatic conditions the W temperature resulting upon expansion of the exhaust fluid causes the moisture entrained by the fluid to congeal and, in consequence the ice may accumulate Within the mufller and seriously diminish the areas of the passages through which the fluid flows to the atmosphere. In order, therefore, to prevent an occurrence of this nature the expansion chamber 42 is provided With a flexible sheet 48, as for example rubber, to confront the exhaust port 28.

In order to assure an undulatcry or flapping motion of the sheet 48 said sheet 48 is suspended from a rivet 49 fastened to the sleeve 3l. A washer 50 is interposed between the sheet and the sleeve 3| to space the sheet a slight distance from the sleeve and thereby -enable the sheet to be freely agitated and flexed by the exhaust fluid issuing from the exhaust port 28 to break up any ice that may form on the sheet.

In practice the present invention has been found to be a highly eiiicient device for suppressing the sound vibrations caused by the intermittent impulses of the exhaust fluid issuing from the piston chamber, During its passage through the sleeve the exhaust fluid passes through successive expansion zones and the impulses are evened out Without causing an appreciable back pressure. The exhaust fluid, therefore, iinally passes through the ports 45 as a substantially constant stream.

I claim:

1. In a muiiling device, the combination of a pneumatic tool casing having a piston chamber and an exhaust port for the piston chamber, a sleeve around the casing to receive exhaust pressure fluid issuing from the exhaust port and having an outlet opening, transverse partitions in the sleeve to divide the interior of the sleeve into compartments, and a conduit extending into the outer ends of adjacent compartments for conveying uid from one compartment to another.

2. In a mufing device, the combination of a pneumatic tool casing having a piston chamber and an exhaust port for the piston chamber, a sleeve around the Icasing to receive exhaust fluid issuing from the exhaust port and having an outlet opening, partitions in the sleeve to divide the interior of the sleeve into compartments, and conduits in the partitions extending into the adjacent compartments to convey fluid from one compartment to another.

3. In a mufling device, the combination of a pneumatic tool casing having a piston chamber and an exhaust for the piston chamber, a sleeve around the casing to receive the exhaust uid issuing from the exhaust port and having an outlet opening, and means agitated by the exhaust fluid to prevent the accumulation of ice Within the sleeve.

4. In a muiliing device, the combination of a pneumatic tool casing having a piston chamber and an exhaust for the piston chamber, a sleeve around the casing to receive the exhaust fluid issuing from the exhaust port and having an outlet opening, and a exible member in the sleeve confronting the exhaust port and being agitated by the exhaust iiui'd to prevent the accumulation of ice Within the sleeve.

WILLIAM A. MORRISON. 

